1. Field of the invention
The present invention relates to an optical disk player, and more particularly to an optical disk player provided with tilt servo unit.
2. Description of Background Information
In an optical video disk player, when disk-shaped recording medium such as video disk (hereinafter simply referred to as "disk") placed on a turntable is warped, the information recording surface of the disk is tilted relative to the optical axis of the information reading light beam, which is irradiated from the pickup, and coma aberration occurs. As the result, the influence of the adjacent track becomes stronger, and this leads to the increase of crosstalk. To overcome this problem, a tilt servo unit is used, which detects the tilt of the information recording surface relative to optical axis of the information reading light beam by a so-called tilt sensor and controls the tilt of the pickup according to the detected output so that the optical axis of the information reading light beam is kept perpendicular to the information recording surface at all times.
As such tilt servo unit, various arrangements have been proposed in the past. Because all of these arrangements have special-purpose tilt sensors near the pickup, and this hinders compact design for pickup and also means the increased production cost.